Synthetic Elastography Using B-Mode Ultrasound Through a Deep Fully Convolutional Neural Network.

Shear-wave elastography (SWE) permits local estimation of tissue elasticity, an important imaging marker in biomedicine. This recently developed, advanced technique assesses the speed of a laterally traveling shear wave after an acoustic radiation force "push" to estimate local Young's moduli in an operator-independent fashion. In this work, we show how synthetic SWE (sSWE) images can be generated based on conventional B-mode imaging through deep learning. Using side-by-side-view B-mode/SWE images collected in 50 patients with prostate cancer, we show that sSWE images with a pixel-wise mean absolute error of 4.5 ± 0.96 kPa with regard to the original SWE can be generated. Visualization of high-level feature levels through t -distributed stochastic neighbor embedding reveals substantial overlap between data from two different scanners. Qualitatively, we examined the use of the sSWE methodology for B-mode images obtained with a scanner without SWE functionality. We also examined the use of this type of network in elasticity imaging in the thyroid. Limitations of the technique reside in the fact that networks have to be retrained for different organs, and that the method requires standardization of the imaging settings and procedure. Future research will be aimed at the development of sSWE as an elasticity-related tissue typing strategy that is solely based on B-mode ultrasound acquisition, and the examination of its clinical utility.

Blind Source Separation for Clutter and Noise Suppression in Ultrasound Imaging: Review for Different Applications.

Blind source separation (BSS) refers to a number of signal processing techniques that decompose a signal into several "source" signals. In recent years, BSS is increasingly employed for the suppression of clutter and noise in ultrasonic imaging. In particular, its ability to separate sources based on measures of independence rather than their temporal or spatial frequency content makes BSS a powerful filtering tool for data in which the desired and undesired signals overlap in the spectral domain. The purpose of this work was to review the existing BSS methods and their potential in ultrasound imaging. Furthermore, we tested and compared the effectiveness of these techniques in the field of contrast-ultrasound super-resolution, contrast quantification, and speckle tracking. For all applications, this was done in silico, in vitro, and in vivo. We found that the critical step in BSS filtering is the identification of components containing the desired signal and highlighted the value of a priori domain knowledge to define effective criteria for signal component selection.

Convective-Dispersion Modeling in 3D Contrast-Ultrasound Imaging for the Localization of Prostate Cancer.

Despite being the solid tumor with the highest incidence in western men, prostate cancer (PCa) still lacks reliable imaging solutions that can overcome the need for systematic biopsies. Dynamic contrast-enhanced ultrasound imaging (DCE-US) allows us to quantitatively characterize the vascular bed in the prostate, due to its ability to visualize an intravenously administered bolus of contrast agents. Previous research has demonstrated that DCE-US parameters related to the vascular architecture are useful markers for the localization of PCa lesions. In this paper, we propose a novel method to assess the convective dispersion (D) and velocity (v) of the contrast bolus spreading through the prostate from three-dimensional (3D) DCE-US recordings. By assuming that D and v are locally constant, we solve the convective-dispersion equation by minimizing the corresponding regularized least-squares problem. 3D multiparametric maps of D and v were compared with 3D histopathology retrieved from the radical prostatectomy specimens of six patients. With a pixel-wise area under the receiver operating characteristic curve of 0.72 and 0.80, respectively, the method shows diagnostic value for the localization of PCa.

The prostate cancer detection rates of CEUS-targeted versus MRI-targeted versus systematic TRUS-guided biopsies in biopsy-naïve men: a prospective, comparative clinical trial using the same patients.

BACKGROUND: The current standard for Prostate Cancer (PCa) detection in biopsy-naïve men consists of 10-12 systematic biopsies under ultrasound guidance. This approach leads to underdiagnosis and undergrading of significant PCa while insignificant PCa may be overdiagnosed. The recent developments in MRI and Contrast Enhanced Ultrasound (CEUS) imaging have sparked an increasing interest in PCa imaging with the ultimate goal of replacing these "blind" systematic biopsies with reliable imaging-based targeted biopsies. METHODS/DESIGN: In this trial, we evaluate and compare the PCa detection rates of multiparametric (mp)MRI-targeted biopsies, CEUS-targeted biopsies and systematic biopsies under ultrasound guidance in the same patients. After informed consent, 299 biopsy-naïve men will undergo mpMRI scanning and CEUS imaging 1 week prior to the prostate biopsy procedure. During the biopsy procedure, a systematic transrectal 12-core biopsy will be performed by one operator blinded for the imaging results and targeted biopsy procedure. Subsequently a maximum of 4 CEUS-targeted biopsies and/or 4 mpMRI-targeted biopsies of predefined locations determined by an expert CEUS reader using quantification techniques and an expert radiologist, respectively, will be taken by a second operator using an MRI-US fusion device. The primary outcome is the detection rate of PCa (all grades) and clinically significant PCa (defined as Gleason score ≥7) compared between the three biopsy protocols. DISCUSSION: This trial compares the detection rate of (clinically significant) PCa, between both traditional systematic biopsies and targeted biopsies based on predefined regions of interest identified by two promising imaging technologies. It follows published recommendations on study design for the evaluation of imaging guided prostate biopsy techniques, minimizing bias and allowing data pooling. It is the first trial to combine mpMRI imaging and advanced CEUS imaging with quantification. TRIAL REGISTRATION: The Dutch Central Committee on Research Involving Human Subjects registration number NL52851.018.15, registered on 3 Nov 2015. Clinicaltrials.gov database registration number NCT02831920 , retrospectively registered on 5 July 2016.

Imaging modalities in focal therapy: multiparametric ultrasound / Modalidades de imágen en Terapia Focal: Ecografía Multiparamétrica

OBJECTIVES: Prostate cancer (PCa) is the most common form of cancer among men in the US and the second most common cause of death. It has been observed that an increasing number of newly diagnosed patients exhibit low-risk features and that over-treatment with radical prostatectomy is a growing problem. The feasibility of focal therapy as an organsparing alternative, however, depends on the reliability of imaging techniques to identify, localize and monitor clinically relevant PCa lesions. The aim of this review is to investigate the potential of multiparametric ultrasound (mpUS) for focal therapy. METHODS: We briefly introduce the most common focal therapies and thoroughly discuss the ability of available ultrasound modalities to localize PCa and Arch. Esp. Urol. 2016; 69 (6): 281-290 281 reflect tissue properties. The imaging requirements of the focal therapies are studied to put the performance of the US techniques into perspective. RESULTS: We found that transrectal greyscale echography, Doppler sonography, elastography, contrast-enhanced ultrasonography and computerized ultrasound have been studied for the purpose of prostate imaging. Several of these modalities are already frequently used in current clinical practice; to add to the diagnostic process of PCa, to guide and monitor the application of focal therapy or to perform follow-up after treatment. Despite their capability to detect a large fraction of the PCa lesions, none of these modalities is currently considered sufficiently accurate for stand-alone tumour detection and localization. However, although there are only few studies reporting on a combined use of different ultrasound modalities, the results of an mpUS approach seem promising. CONCLUSION: Several US modalities have been successfully applied as a viable alternative to monitor tissue destruction during and after treatment. In view of the advantages of US and the promising results of a multiparametric approach in PCa detection and localization, researchers are urged to further investigate mpUS for therapeutic purposes

OBJETIVO: El cáncer de próstata es la forma de cáncer más común en hombres en los EEUU y la segunda causa más frecuente de muerte. Se ha observado que un número creciente de pacientes de nuevo diagnóstico presentan características de bajo riesgo y que el sobretratamiento con prostatectomía radical es un problema creciente. La viabilidad de la terapia focal como alternativa con conservación del órgano, sin embargo, depende de la fiabilidad de las técnicas de imagen para identificar, localizar y monitorizar lesiones de cáncer de próstata clínicamente relevantes. El objetivo de esta revisión es investigar el potencial de la ecografía multiparamétrica (ECOmp) para la terapia focal. MÉTODOS: Introducimos brevemente las formas de terapia focal más frecuentes y discutimos a fondo la habilidad de las modalidades disponibles de ecografía para localizar el CaP y reflejar las propiedades de los tejidos. Se estudian los requerimientos de imagen para terapias focales para poner en perspectiva el desempeño de las técnicas de ecografía. RESULTADOS: Encontramos que la ecografía en escala de grises, la ecografía Doppler, la elastografía, la ecografía con contraste y la ecografía computarizada se han estudiado con el propósito de evaluar por imagen la próstata. Varias de estas modalidades se utilizan ya frecuentemente en la práctica clínica actual; para sumar en el proceso diagnóstico del CaP, para guiar y monitorizar la aplicación de terapia focal o realizar el seguimiento después del tratamiento. A pesar de su capacidad para detectar una gran fracción de las lesiones de CaP, ninguna de estas modalidades se considera actualmente suficientemente precisa para la detección y localización de tumores como prueba única. Sin embargo, aunque hay pocos estudios que comuniquen el uso combinado de diferentes modalidades de ultrasonido, los resultados de un abordaje multiparamétrico con ecografía parecen prometedores. CONCLUSION: Se han aplicado con éxito varias modalidades de ecografía como una alternativa viable para monitorizar la destrucción de tejido durante y después del tratamiento. En vista de las ventajas de la ecografía y de los prometedores resultados de un abordaje multiparamétrico en la detección y localización del CaP, se urge a los investigadores a investigar más la ecografía multiparamétrica con fines terapéutico

Imaging modalities in Focal Therapy: Multiparametric Ultrasound.

OBJECTIVES: Prostate cancer (PCa) is the most common form of cancer among men in the US and the second most common cause of death. It has been observed that an increasing number of newly diagnosed patients exhibit low-risk features and that over-treatment with radical prostatectomy is a growing problem. The feasibility of focal therapy as an organsparing alternative, however, depends on the reliability of imaging techniques to identify, localize and monitor clinically relevant PCa lesions. The aim of this review is to investigate the potential of multiparametric ultrasound (mpUS) for focal therapy. METHODS: We briefly introduce the most common focal therapies and thoroughly discuss the ability of available ultrasound modalities to localize PCa and reflect tissue properties. The imaging requirements of the focal therapies are studied to put the performance of the US techniques into perspective. RESULTS: We found that transrectal greyscale echography, Doppler sonography, elastography, contrast-enhanced ultrasonography and computerized ultrasound have been studied for the purpose of prostate imaging. Several of these modalities are already frequently used in current clinical practice; to add to the diagnostic process of PCa, to guide and monitor the application of focal therapy or to perform follow-up after treatment. Despite their capability to detect a large fraction of the PCa lesions, none of these modalities is currently considered sufficiently accurate for stand-alone tumour detection and localization. However, although there are only few studies reporting on a combined use of different ultrasound modalities, the results of an mpUS approach seem promising. CONCLUSION: Several US modalities have been successfully applied as a viable alternative to monitor tissue destruction during and after treatment. In view of the advantages of US and the promising results of a multiparametric approach in PCa detection and localization, researchers are urged to further investigate mpUS for therapeutic purposes.

MRI and contrast-enhanced ultrasound imaging for evaluation of focal irreversible electroporation treatment: results from a phase I-II study in patients undergoing IRE followed by radical prostatectomy.

OBJECTIVES: Irreversible electroporation (IRE) is an ablative therapy with a low side-effect profile in prostate cancer. The objective was: 1) To compare the volumetric IRE ablation zone on grey-scale transrectal ultrasound (TRUS), contrast-enhanced ultrasound (CEUS) and multiparametric MRI (mpMRI) with histopathology findings; 2) To determine a reliable imaging modality to visualize the IRE ablation effects accurately. METHODS: A prospective phase I-II study was performed in 16 patients scheduled for radical prostatectomy (RP). IRE of the prostate was performed 4 weeks before RP. Prior to, and 4 weeks after the IRE treatment, imaging was performed by TRUS, CEUS, and mpMRI. 3D-analysis of the ablation volumes on imaging and on H&E-stained whole-mount sections was performed. The volumes were compared and the correlation was calculated. RESULTS: Evaluation of the imaging demonstrated that with T2-weighted MRI, dynamic contrast enhanced (DCE) MRI, and CEUS, effects of IRE are visible. T2MRI and CEUS closely match the volumes on histopathology (Pearson correlation r = 0.88 resp. 0.80). However, IRE is not visible with TRUS. CONCLUSIONS: mpMRI and CEUS are appropriate for assessing IRE effects and are the most feasible imaging modalities to visualize IRE ablation zone. The imaging is concordant with results of histopathological examination. KEY POINTS: • mpMRI and contrast-enhanced ultrasound are appropriate imaging modalities for assessing IRE effects • mpMRI and CEUS are the most feasible imaging modalities to visualize IRE ablation zone • The imaging is concordant with results of histopathological examination after IRE • Grey-scale US is insufficient for assessing IRE ablations.

The correlation between the electrode configuration and histopathology of irreversible electroporation ablations in prostate cancer patients.

PURPOSE: Irreversible electroporation (IRE) is a novel minimally invasive therapy for prostate cancer using short electric pulses to ablate prostate tissue. The purpose of this study is to determine the IRE effects in prostate tissue and correlate electrode configuration with the histology of radical prostatectomy (RP) specimens. We hypothesize that the area within the electrode configuration is completely ablated and that the area within the electrode configuration is predictive for the ablated area after treatment. METHODS: A prospective phase I/II study was conducted in 16 consecutive patients with histopathologically confirmed prostate cancer scheduled for RP. Focal or extended IRE treatment of the prostate was performed 4 weeks prior to RP. The locations of the electrodes were used to calculate the planned ablation zone. Following RP, the specimens were processed into whole-mount sections, histopathology (PA) was assessed and ablation zones were delineated. The area of the tissue alteration was determined by measuring the surface. The planned and the histological ablation zones were compared, analysed per individual patient and per protocol (focal vs. extended). RESULTS: All cells within the electrode configuration were completely ablated and consisted only of necrotic and fibrotic tissue without leaving any viable cells. The histological ablation zone was always larger than the electrodes configuration (2.9 times larger for the 3 electrodes configuration and 2.5 times larger for the ≥4 electrode configuration). These ablation effects extended beyond the prostatic capsule in the neurovascular bundle in 13 out of 15 cases. CONCLUSIONS: IRE in prostate cancer results in completely ablated, sharply demarcated lesions with a histological ablation zone beyond the electrode configuration. No skip lesions were observed within the electrode configuration. CLINICAL TRIALS: ClinicalTrials.gov Identifier: NCT01790451 https://clinicaltrials.gov/ct2/show/NCT01790451.

[Advances in ultrasound techniques for the diagnosis and staging of prostate cancer. Elastography, Doppler ultrasound, ultrasound contrast media, ultrasound quantification media and MRI fusion]. / Avances en las Técnicas Ecográficas para el diagnóstico y estadiaje del cáncer de próstata. Elastografía, Ecografía doppler, Contrastes Ecográficos, Métodos de Cuantificación ecográfica y fusión con Resonancia Magnética Nuclear.

OBJECTIVES: Transrectal ultrasound-guided prostate biopsy remains the gold standard in the diagnosis of prostate cancer. Various Ultrasound modalities have been proposed to increase the cancer detection rate. Our purpose is to evaluate each of these methods , and to present its current literature and clinical utility. METHOD: A non structured review of the current literature was conducted over these different various ultrasound modalities used during the transrectal ultrasound-guided prostate biopsied in the diagnosis of prostate cancer. RESULTS: The data investigation of the various modalities associated sonographic features exhibits great heterogeneity and highly variable results. Some new techniques sampling present promising results with high sensitivity and specificity, thus increasing the diagnostic yield of transrectal biopsy. It seems that elastography shows encouraging figures, especially given the recent introduction of the "shearvawe" elastography that decreases the user-dependent factor. CONCLUSIONS: The ultrasound-guided prostate biopsy has an acceptable sensitivity in the diagnosis of prostate cancer, but its specificity is still low. Various modalities associated with ultrasound are available in clinical practice in order to increase cancer detection rate. Although some promising data have been published for some of the modalities, we believe the combination of these includes validated ultrasound guided biopsy protocols to accurately target and diagnose prostate cancer.

Avances en las Técnicas Ecográficas para el diagnóstico y estadiaje del cáncer de próstata. Elastografía, Ecografía doppler, Contrastes Ecográficos, Métodos de Cuantificación ecográfica y fusión con Resonancia Magnética Nuclear / Advances in ultrasound techniques for the diagnosis and staging of prostate cancer. Elastography, Doppler ultrasound, ultrasound contrast media, ultrasound quantification media and MRI fusion

OBJETIVO: La biopsia prostática transrectal sistematica eco-guiada sigue siendo el procedimiento estándar en el diagnóstico del cáncer de próstata. Diversas modalidades ecográficas asociadas han sido propuestas. Nuestro propósito es evaluar cada una de estas modalidades, y presentar su estado actual en la literatura y utilidad clínica. MÉTODO: Revisión no estructurada de la literatura sobre la utilidad actual de los diversos modos y tipos de ecografía usados durante la biopsia prostática transrectal eco-guiada en el diagnóstico de cáncer de próstata. RESULTADOS: Las cifras publicadas sobre las distintas modalidades ecográficas asociadas presentan gran heterogeneidad y resultados muy variables. Algunas nuevas técnicas muestras resultados prometedores, con alta sensibilidad y especificidad, aumentando así el rendimiento de la biopsia transrectal convencional, acercándose a la biopsia eco-dirigida como objetivo último. La elastografía y la fusión de Resonancia Magnetica Nuclear (RMN)/Ecografia parecen mostrar cifras alentadoras, especialmente la primera, dada la reciente introducción de la elastografía "shearwave" que disminuye el factor usuario-dependiente, aumentando considerablemente los índices de detección. CONCLUSIONES: La biopsia prostática sistematica eco-guiada tiene una sensibilidad aceptable en el diagnóstico del cáncer de próstata, pero su especificidad es baja . Diversas modalidades asociadas a la ecografía están disponibles con el objetivo de aumentar su rendimiento. Aunque alentadores, los resultados se han publicado en forma aislada; creemos que la combinación de estas modalidades junto con protocolos validados de visualización serán los que lograrán un procedimiento de precisión en el diagnóstico del cáncer de próstata

OBJECTIVE: Transrectal ultrasoundguided prostate biopsy remains the gold standard in the diagnosis of prostate cancer. Various Ultrasound modalities have been proposed to increase the cancer detection rate. Our purpose is to evaluate each of these methods, and to present its current literature and clinical utility. METHOD: A non structured review of the current literature was conducted over these different various ultrasound modalities used during the transrectal ultrasound-guided prostate biopsied in the diagnosis of prostate cancer. RESULTS: The data investigation of the various modalities associated sonographic features exhibits great heterogeneity and highly variable results. Some new techniques sampling present promising results with high sensitivity and specificity, thus increasing the diagnostic yield of transrectal biopsy. It seems that elastography shows encouraging figures, especially given the recent introduction of the "shearvawe" elastography that decreases the user-dependent factor. CONCLUSIONS: The ultrasound-guided prostate biopsy has an acceptable sensitivity in the diagnosis of prostate cancer, but its specificity is still low. Various modalities associated with ultrasound are available in clinical practice in order to increase cancer detection rate. Although some promising data have been published for some of the modalities, we believe the combination of these includes validated ultrasound guided biopsy protocols to accurately target and diagnose prostate cancer

Follow-up modalities in focal therapy for prostate cancer: results from a Delphi consensus project.

INTRODUCTION: Focal therapy can offer the middle ground for treatment between active surveillance and radical therapy in patients with low- and intermediate-risk prostate cancer. Factors that prohibit focal therapy from being standard of care are numerous. Several consensus projects have been conducted to position the utilization of imaging and trial design in focal therapy. However, the literature is still scarce on patient follow-up after focal therapy. For these reasons, an international multidisciplinary consensus project was established in order to reach consensus about a uniform follow-up protocol after focal therapy. OBJECTIVE: To standardize patient follow-up after focal therapy. MATERIALS AND METHODS: A literature study was performed, and a questionnaire was constructed. The questionnaire was sent out to 76 participants (70 % urologists, 28 % radiologists and 2 % biomedical engineers) in three consecutive rounds according to the Delphi method. In each round, the panelists were presented with the results of the previous round. Participants each had the opportunity to adapt, delete or add questions. The topics discussed pertaining to follow-up after focal therapy were as follows: (1) general,(2) biopsies, (3) PSA, (4) digital rectal examination (DRE), (5) imaging, (6) quality of life (QoL) and (7) registration and pooling of data. The project was concluded with a face-to-face meeting in which final conclusions were formulated. RESULTS: The follow-up after focal therapy should be a minimum of 5 years. The following modalities should be included in assessing post-treatment outcomes: multiparametric MRI (mpMRI), biopsies, assessment of erectile function, QoL, urinary symptoms and incontinence. A systematic 12-core TRUS biopsy combined with 4-6 targeted biopsy cores of the treated area and any suspicious lesion(s) should be performed after 1 year, and thereafter only when there is suspicion on imaging. The ideal way to perform targeted biopsies is to use TRUS-MRI fusion technology. PSA should be performed for research purposes, in the first year, every 3 months, and after the first year, every 6 months. mpMRI is the optimal imaging modality for follow-up after focal therapy. On a 1.5T scanner, an endorectal coil is strongly advised by the panel, whereas on a 3T machine, it is optional, however, it will improve image quality. The following sequences should be included: T2WI, DWI including high b values of >1,000 and ADC maps of DWI, DCE and T1WI. Imaging should be performed at 6 months and at 1 year following treatment; after the first year post-treatment, it should be performed every year until 5 years following treatment. All data should ideally be pooled in a common global database. CONCLUSION: Focal therapy is a relatively new form of treatment for prostate cancer. In order to include focal therapy as a standard of care treatment, consistent follow-up is necessary. By implementing the results of this consensus study, focal therapy users will be able to provide important and standardized outcome data.

The safety and efficacy of irreversible electroporation for the ablation of prostate cancer: a multicentre prospective human in vivo pilot study protocol.

INTRODUCTION: Current surgical and ablative treatment options for prostate cancer have a relatively high incidence of side effects, which may diminish the quality of life. The side effects are a consequence of procedure-related damage of the blood vessels, bowel, urethra or neurovascular bundle. Ablation with irreversible electroporation (IRE) has shown to be effective in destroying tumour cells and harbours the advantage of sparing surrounding tissue and vital structures. The aim of the study is to evaluate the safety and efficacy and to acquire data on patient experience of minimally invasive, transperineally image-guided IRE for the focal ablation of prostate cancer. METHODS AND ANALYSIS: In this multicentre pilot study, 16 patients with prostate cancer who are scheduled for a radical prostatectomy will undergo an IRE procedure, approximately 30 days prior to the radical prostatectomy. Data as adverse events, side effects, functional outcomes, pain and quality of life will be collected and patients will be controlled at 1 and 2 weeks post-IRE, 1 day preprostatectomy and postprostatectomy. Prior to the IRE procedure and the radical prostatectomy, all patients will undergo a multiparametric MRI and contrast-enhanced ultrasound of the prostate. The efficacy of ablation will be determined by whole mount histopathological examination, which will be correlated with the imaging of the ablation zone. ETHICS AND DISSEMINATION: The protocol is approved by the ethics committee at the coordinating centre (Academic Medical Center (AMC) Amsterdam) and by the local Institutional Review Board at the participating centres. Data will be presented at international conferences and published in peer-reviewed journals. CONCLUSIONS: This pilot study will determine the safety and efficacy of IRE in the prostate. It will show the radiological and histopathological effects of IRE ablations and it will provide data to construct an accurate treatment planning tool for IRE in prostate tissue. TRIAL REGISTRATION NUMBER: Clinicaltrials.gov database: NCT01790451.

Closed-form solution of the convolution integral in the magnetic resonance dispersion model for quantitative assessment of angiogenesis.

Prostate cancer (PCa) diagnosis and treatment is still limited due to the lack of reliable imaging methods for cancer localization. Based on the fundamental role played by angiogenesis in cancer growth and development, several dynamic contrast enhanced (DCE) imaging methods have been developed to probe tumor angiogenic vasculature. In DCE magnetic resonance imaging (MRI), pharmacokinetic modeling allows estimating quantitative parameters related to the physiology underlying tumor angiogenesis. In particular, novel magnetic resonance dispersion imaging (MRDI) enables quantitative assessment of the microvascular architecture and leakage, by describing the intravascular dispersion kinetics of an extravascular contrast agent with a dispersion model. According to this model, the tissue contrast concentration at each voxel is given by the convolution between the intravascular concentration, described as a Brownian motion process according to the convective-dispersion equation, with the interstitium impulse response, represented by a mono-exponential decay, and describing the contrast leakage in the extravascular space. In this work, an improved formulation of the MRDI method is obtained by providing an analytical solution for the convolution integral present in the dispersion model. The performance of the proposed method was evaluated by means of dedicated simulations in terms of estimation accuracy, precision, and computation time. Moreover, a preliminary clinical validation was carried out in five patients with proven PCa. The proposed method allows for a reduction by about 40% of computation time without any significant change in estimation accuracy and precision, and in the clinical performance.

Prostate cancer localization by novel magnetic resonance dispersion imaging.

Diagnosis and focal treatment of prostate cancer, the most prevalent form of cancer in men, is hampered by the limits of current clinical imaging. Angiogenesis imaging is a promising option for detection and localization of prostate cancer. It can be imaged by dynamic contrast-enhanced (DCE) MRI, assessing microvascular permeability as an indicator for angiogenesis. However, information on microvascular architecture changes associated with angiogenesis is not available. This paper presents a new model enabling the combined assessment of microvascular permeability and architecture. After the intravenous injection of a gadolinium-chelate bolus, time-concentration curves (TCCs) are measured by DCE-MRI at each voxel. According to the convective dispersion equation, the microvascular architecture is reflected in the dispersion coefficient. A solution of this equation is therefore proposed to represent the intravascular blood plasma compartment in the Tofts model. Fitting the resulting model to TCCs measured at each voxel leads to the simultaneous generation of a dispersion and a permeability map. Measurement of an arterial input function is no longer required. Preliminary validation was performed by spatial comparison with the histological results in seven patients referred for radical prostatectomy. Cancer localization by the obtained dispersion maps provided an area under the receiver operating characteristic curve equal to 0.91. None of the standard DCE-MRI parametric maps could outperform this result, motivating towards an extended validation of the method, also aimed at investigating other forms of cancer with pronounced angiogenic development.

Contrast-ultrasound dispersion imaging for prostate cancer localization by improved spatiotemporal similarity analysis.

Angiogenesis plays a major role in prostate cancer growth. Despite extensive research on blood perfusion imaging aimed at angiogenesis detection, the diagnosis of prostate cancer still requires systematic biopsies. This may be due to the complex relationship between angiogenesis and microvascular perfusion. Analysis of ultrasound-contrast-agent dispersion kinetics, determined by multipath trajectories in the microcirculation, may provide better characterization of the microvascular architecture. We propose the physical rationale for dispersion estimation by an existing spatiotemporal similarity analysis. After an intravenous ultrasound-contrast-agent bolus injection, dispersion is estimated by coherence analysis among time-intensity curves measured at neighbor pixels. The accuracy of the method is increased by time-domain windowing and anisotropic spatial filtering for speckle regularization. The results in 12 patient data sets indicated superior agreement with histology (receiver operating characteristic curve area = 0.88) compared with those obtained by reported perfusion and dispersion analyses, providing a valuable contribution to prostate cancer localization.

[Imaging of the prostate]. / Lokale Bildgebung der Prostata.

Recently several new technologies for prostate imaging have been developed. The aim of these technologies was to improve the diagnosis of prostate cancer. Especially the transrectal ultrasound (TRUS) has been refined to the so-called enhanced ultrasound, as regular grey scale TRUS has limited ability to identify cancer lesions in the prostate. In several studies elastography has shown good capability to identify cancer lesions in the prostate as well as to absolutely increase the detection rate of randomized biopsies by up to 10 %.. Contrast-enhanced ultrasound shows varying results in the published literature with increased detection rates on the one hand and unchanged detection rates relative to randomized biopsy on the other hand. The online available ANNA/C-TRUS system shows detection rates with six targeted biopsies that are comparable to the published detection rates of randomized saturation biopsies. Direct systematic comparison to randomized biopsies is missing. The Histoscanning system currently provides the poorest data as no biopsy studies are available. Multicenter trials are mandatory for all new imaging technologies in order to implement them as standard into clinical practice.

Evaluation of renal masses with contrast-enhanced ultrasound.

The clinical need for characterising small renal masses (SRMs) is increasing due to their rising incidental detection. This increase is especially seen in younger and older generations and concerns mainly SRMs. Diagnostics is mainly made by contrast-enhanced CT or MRI. However, these imaging methods fail to accurately distinguishing benign from malignant SRMs. Other disadvantages of CT or MRI are high costs, the use of ionizing radiation, nephrotoxicity induced by iodine contrast agents or nephrogenic systemic fibrosis (NSF) induced by gadolinium contrast agents. Contrast-enhanced ultrasound (CEUS) is based on ultrasonography and microbubbles to real-time visualize the renal blood flow without the use of nephrotoxic agents or ionizing radiation. This comprehensive review evaluates the capabilities of CEUS in the diagnostics of benign (angiomyolipomas, cysts, oncocytomas, pseudotumors) and malignant masses (renal cell carcinomas), and focuses on possible future treatment.

What is the added value of combined core biopsy and fine needle aspiration in the diagnostic process of renal tumours?

PURPOSE: Non-diagnostic results still hinder the routine use of core biopsy (CB) and fine needle aspiration (FNA) in the diagnostic process of renal tumours. Furthermore, substantial interobserver variability has been reported. We assessed the added value of combining the results of CB and FNA by five pathologists in the ex vivo diagnosis of renal mass. METHODS: Two ex vivo core biopsies were taken followed by two FNA passes from extirpated tumours. All samples were evaluated by five blinded pathologists. A consensus diagnosis of the surgical specimen was the index for comparison. For each pathologist, the number of non-diagnostic (non-conclusive or undetermined biology and failed biopsies), correct and incorrect scored cases of each technique was assessed. When a non-diagnostic CB or FNA had a correct diagnostic counterpart, this was considered as of added value. RESULTS: Of the 57 assessed tumours, 53 were malignant. CB was non-diagnostic in 4-10 cases (7-17.5%). FNA established the correct diagnosis in 1-7 of these cases. FNA was non-diagnostic in 2-6 cases (3.5-10.5%), and the counterpart CB established the correct diagnosis in 1-6 of these cases. For the 5 pathologists, accuracy of CB and FNA varied between 82.5-93% and 89.5-96.5%, respectively. Combination of both types of biopsy resulted in 55-57 correct results (accuracy 96.5-100%), i.e., an increase in accuracy of 3.5-14%. CONCLUSION: Combining the result of CB and FNA in renal mass biopsy leads to a higher diagnostic accuracy. Recommendations on which technique used should be adapted to local expertise and logistic possibilities.

Focal therapy in prostate cancer-report from a consensus panel.

PURPOSE: To establish a consensus in relation to case selection, conduct of therapy, and outcomes that are associated with focal therapy for men with localized prostate cancer. MATERIAL AND METHODS: Urologic surgeons, radiation oncologists, radiologists, and histopathologists from North America and Europe participated in a consensus workshop on focal therapy for prostate cancer. The consensus process was face to face within a structured meeting, in which pertinent clinical issues were raised, discussed, and agreement sought. Where no agreement was possible, this was acknowledged, and the nature of the disagreement noted. RESULTS: Candidates for focal treatment should have unilateral low- to intermediate-risk disease with clinical stage

Speckle-initialized dynamic segmentation of the prostate.

Echography is a commonly used modality for prostate imaging. Prostate segmentation is the first step in analyzing echographic prostate images. Because of the nature of these images, traditional local image processing operators are inadequate for finding the prostate boundary. Most automated segmentations described in literature require user interaction for contour initializing or editing. Also shape templates are applied as prior knowledge. In this paper, an automatic segmentation method is presented, based on prostate specific image granulation and image intensity. First, a granulation detector is used to extract granulation. Subsequently, the Hessian is adopted to evaluate granulation shape and intensity for the extraction of the prostate-specific dot pattern. This dot pattern is used to construct the contour initialization. A smooth contour model (discrete dynamic contour; DDC) is evolved from this initialization to the final contour. The guiding vector field for the DDC deformation is the gradient vector flow field calculated from an edge map of the original image. The scale of the relevant edges (large compared to granulation) is estimated from the prostate-specific dot pattern. Comparison of automated segmentations with clinical expert manual segmentations reveals a mean sensitivity and accuracy of 0.90 and 0.93, respectively.